1. Field of the Invention
The presently disclosed subject matter relates to an image pickup apparatus and a restoration gain data generation method and, more particularly, to a technique for omitting a focusing mechanism for mechanical focusing and obtaining a high-quality image signal.
2. Description of the Related Art
There has been proposed an image restoration apparatus whose imaging optical system has a depth of focus extended by inserting a phase plate (optical wavefront modulation element) for phase modulation in an optical path of the imaging optical system and which restores an image blurred due to the extended depth of focus (a larger point image) to a high-resolution image (a smaller point image) by subjecting the blurred image to filtering processing using a restoration filter (Japanese Patent Application Laid-Open No. 2009-89082).
As illustrated in FIGS. 9A to 9C, the image restoration apparatus described in Japanese Patent Application Laid-Open No. 2009-89082 uses restoration filters prepared for the respective colors of R, Gr, B, and Gb for pieces of RAW data (Portion B of FIG. 9A) of the colors of R (red), G (green), and B (blue) outputted from a color image pickup element (Portion A of FIG. 9A) having color filters arranged in the Bayer pattern to perform filtering processing (deconvolution processing) using one of the restoration filters corresponding to the color of a pixel of interest on a pixel-by-pixel basis (FIG. 9B) and, more particularly, perform restoration processing on pieces of RAW data to be subjected to Bayer pattern interpolation. The image restoration apparatus is configured to reduce the workload by performing restoration processing on one image in the Bayer pattern instead of performing restoration processing on three images of R, G, and B.